Non-Propeller Fan

ABSTRACT

A fan that moves a fluid that includes a flexible membrane with a length defining a long axis that includes at least two supported ends, a support structure that supports the supported ends of the flexible membrane  2  and provides a tension between the two supported ends of the flexible membrane, and a displacement device that vibrates the flexible membrane at a frequency to move the fluid in a direction substantially perpendicular to the long axis of the flexible membrane. The fan may be used with a MEMS device, with a larger circuit, a solidstate lighting device, or with a room within a house or any other suitable application or scale.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/288,184, filed 18 Dec. 2009, which is incorporated in its entirety by this reference.

TECHNICAL FIELD

This invention relates generally to the fluid movement field, and more specifically to a new and useful non-propeller fan in the fan field.

BACKGROUND

Generating fluid flow with rotating airfoil-based fans is substantially well known in the art. The disadvantages of these devices in certain situations are also well known in the art, and there have been numerous improvements within the art of flow generation over the past 50 years. However, all such improvements continue to be lacking in some important respects, particularly in situations where the environment is space-constrained (as with cooling the electronics in a mobile phone or individual high-power LEDs, for instance), corrosive, and/or where safety and energy efficiency is of paramount importance.

In these situations, a flow generating device that obviates the need for rotating airfoils is advantageous. One such class of devices, as exemplified by Busch et al. in U.S. patent application Ser. No. 12/635,325, known as oscillating diaphragm fans or jet generators has been advanced to operate in some of these unique situations. However, such devices typically require a moving piston, a plastic or metal enclosure or housing, a nozzle, and/or a series of valves. These devices also typically require a particular distance between the object to be cooled and the jet-forming housing, and further require a housing of such complexity that size reduction possibilities are restricted. Projecting flow into a variety of planes, such as perpendicular to the moving piston, is also difficult or impossible for this class of device.

Other attempts at non-rotating-airfoil based fans have been made in the consumer market as well, most recently by Dyson with the Air Multiplier™ fan. This design improves the safety of general use room-fans, and marginally improves the quality of airflow, but still requires a hidden traditional rotating airfoil fan to accelerate air past a fixed airfoil. Thus, there is a need in the fluid movement field to create an new and useful means and method for moving fluid without a rotating airfoil and without the substantial space restrictions as seen in the art.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a representation of a variation of the fan of a first preferred embodiment with induced flow substantially perpendicular to the long axis of the flexible membrane.

FIG. 2 is a representation of a variation of the fan of a second preferred embodiment with induced flow substantially perpendicular to the long axis of the flexible membrane.

FIGS. 3 a and 3 b are representations of an exemplary application of the fan of the preferred embodiments to cool a chip on a printed circuit board in a first and second arrangement variation.

FIGS. 4 a and 4 b are representations of a first and a second mode of vibration of the flexible membrane with a bending motion with fluid flow induced along the main surface of the membrane.

FIGS. 5 a and 5 b are representations of vibration of the flexible membrane with torsional motion.

FIG. 6 is a representation of the fan of the preferred embodiments including a mass.

FIG. 7 is a representation of a preferred manufacturing method of a microscale (MEMS) variation of the fan of the preferred embodiments.

FIGS. 8 a and 8 b are representations of a first and second variation of a support structure that directs airflow.

FIG. 9 is a representation of the fan of the preferred embodiments including a plurality of flexible membranes.

FIGS. 10 a and 10 b are representations of the fan of the preferred embodiments including a rotating element that rotates the flexible membrane.

FIGS. 11 a and 11 b are representations of the movement of the flexible membrane when first and second magnetic fields of the first preferred embodiment that are oriented parallel to each other interact.

FIG. 11 c is a representation of first and second magnetic fields of the first preferred embodiment that are perpendicular to each other.

FIG. 12 is a representation of a variation of the fan of the first preferred embodiment with two conductors from a side view.

FIG. 13 is a representation of a second variation of the first preferred embodiment with a magnet displacement device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiments of the invention is not intended to limit the invention to these preferred embodiments, but rather to enable any person skilled in the art of to make and use this invention.

As shown in FIGS. 1-3, the fan 100 of the preferred embodiments functions to move a fluid, preferably air, to increase the rate of heat transfer. The fan 100 of the preferred embodiments may be used as a MEMS (Micro Electro-Mechanical Systems) device, as shown in FIG. 7, and integrated with a processing chip to cool the processing chip. Alternatively, in a larger scale, the fan 100 of the preferred embodiments may be used to cool a room within a house. The fan 100 of the preferred embodiments may also be of a size in between a MEMS device and a large scale device, for example, the fan 100 may be mounted on a printed circuit board, as shown in FIGS. 3 a and 3 b. However, any other suitable scale and/or application of the fan 100 may be used. The fan 100 of the preferred embodiments is preferably one of two preferred embodiments. As shown in FIG. 1, the fan 100 of a first preferred embodiment includes a flexible membrane 2 including at least two supported ends and a length between the two supported ends 22 and 24 that defines a long axis 20, a support structure 6 that supports the supported ends 22 and 24 of the flexible membrane 2 and provides a tension between the two supported ends 22 and 24 of the flexible membrane 2, a first magnet 12 that generates a first magnetic field, and a second magnet 14 that generates a second magnetic field that interacts with the first magnetic field and fluctuates relative to the first magnetic field to cause the membrane to vibrate at a frequency and to move the fluid in a direction substantially perpendicular to the long axis 20 of the flexible membrane 2. As shown in FIG. 2, the fan 100 of a second preferred embodiment includes a flexible membrane 2 including at least two supported ends and a length between the two supported ends 22 and 24 that defines a long axis 20, wherein at least a portion of the a flexible membrane 2 includes a shape changing material 30, a support structure 6 that supports the supported ends 22 and 24 of the flexible membrane 2 and provides a tension to the flexible membrane 2 between the two supported ends 22 and 24, and a power source 5 coupled to the shape changing material that provides power to change the shape of the shape changing material to vibrate the flexible membrane 2 at a frequency and to move the fluid in a direction substantially perpendicular to the long axis 20 of the flexible membrane 2. Both the first and second preferred embodiments function to move fluid in a particular flow rate and/or direction. The first and second preferred embodiments may also function to move fluid at adjustable flow rates and/or directions. The fan 100 of the preferred embodiments may also be a combination of the first and second preferred embodiments or any other suitable embodiment that moves air using a flexible membrane that is held in tension between at least two supported ends. This movement of air may be caused directly from the forces imparted by the flexible membrane or by pressure gradients generated by the membranes movement.

As described above, the fan 100 of the preferred embodiments preferably moves ambient air. This reduces or eliminates the need for additional pumps that provide an alternative fluid, which may decrease the complexity of the cooling system. The fan 100 may alternatively also be thought of as moving fluid at ambient pressure, decreasing the need for pumps that increases the pressure of a fluid (such as ambient air). By utilizing ambient air, the fan 100 may also be arranged in a variety of locations relative to the object and/or area that is to be cooled. For example, the fan 100 may be located substantially adjacent to a chip that is to be cooled (such as to the side or over the chip) as shown in FIG. 3, which may allow more efficient cooling. The fan 100 is preferably arranged in substantially the same plane as the component to be cooled or in a plane substantially parallel to the object to be cooled. In this example, the circuit board may function as the support structure 6. In a second example, the fan 100 may be located substantially outside of a room that is to be cooled and functions to move fluid through an air duct or any other suitable fluid passageway coupled to the room. However, any other suitable arrangement of the fan 100 may be used. The fan 100 of the preferred embodiments provides a solution to moving fluids that does not require a propeller or rotational motor, which may decrease maintenance needs and increase the efficiency of the conversion of electrical energy into a fluid moving force due to the relative lack of grinding parts that may lead to friction and abrasion. In a third example, the fan 100 may be located within a tank of fluids and may be used to cause fluid flow within the tank to stir the fluids. This may be particularly useful where moving parts such as a motor may suffer damage when submerged within the fluid. The fan 100 of the preferred embodiments includes a relatively small number of moving parts and substantially few grinding parts that may suffer damage in such situations. Similarly, with a relative lack of grinding parts, debris that may result from grinding of parts is decreased, which may be substantially useful in stirring fluids that are to be kept uncontaminated. The membrane 2 may also be composed of substantially chemically inert materials to decrease chemical reactions with the fluid within the tank. Additionally, due to the pliable nature of the membrane 2, the fan 100 of the preferred embodiments may be better suited to accommodate to the geometry of the tank. However, any other suitable use of the fan 100 may be used.

The flexible membrane 2 functions to move air in a direction substantially perpendicular to the long axis 20 of the flexible membrane 2 when moved. The flexible membrane 2 preferably creates a fluid flow that is turbulent, which may provide increased cooling over laminar fluid flow, but may alternatively create any other suitable type of fluid flow. As shown in the FIGS. 1 and 2, the flexible membrane 2 preferably includes a main surface that defines a rest plane when the fan 100 is at rest and two side surfaces. The main surface of the flexible membrane 2 is preferably of an elongated shape (for example, a rectangle or airfoil surface) and is supported and/or fixated at two ends and preferably moves fluid in a direction perpendicular to the long axis 20 of the flexible membrane 2. The flexible membrane 2 may move air in a direction substantially along the rest plane defined by the main surface of the flexible membrane 2, as shown in FIGS. 4 a and 4 b. The main surface of the flexible membrane 2 may be tapered or any other suitable geometry that may offer significant advantages in moving fluid, fluid flow rate, and/or direct the fluid in a desired direction. For example, as shown in FIG. 3, the fan 100 may be used to direct airflow towards a chip. The cross section of the flexible membrane 2 is also preferably rectangular, but may also be tapered, of substantially an airfoil shape to enhance the oscillation characteristics of the elongated flexible membrane, to direct fluid flow in the desired direction, and/or to increase the fluid flow rate. However, any other suitable geometry for the flexible membrane 2 may be used.

The flexible membrane 2 may vibrate in a bending motion, as shown in FIGS. 4 a and 4 b. The flexible membrane 2 of this variation preferably oscillates in a first mode (shown in FIG. 4 a), but may alternatively oscillate in a second mode where three nodes and two antinodes are formed (shown FIG. 4 b). However, any other suitable number of oscillation nodes along the membrane 2 may be used. Alternatively, the flexible membrane 2 may alternatively vibrate in a torsional motion, as shown in FIGS. 5 a and 5 b. The flexible membrane 2 may alternatively vibrate in a combination of bending and torsional motion, for example, as seen in the wing of a manta ray. However, any other suitable form of vibration or oscillation may be induced in the flexible membrane 2 to cause fluid flow across the membrane 2 at any suitable direction.

The flexible membrane 2 may also include a mass 62, as shown in FIG. 6, that functions to facilitate the desired vibration of the flexible membrane 2. The mass 62 may be a weight element that is mounted onto the membrane, but may alternatively be incorporated into the membrane (for example, a material that is molded into the membrane). The mass 62 may also function as either the first or second magnet, but may alternatively be any other suitable mass that affects the vibration of the flexible membrane 2. For example, the mass may be located substantially to the side of the long axis 20 to cause the flexible membrane 2 to be unbalanced and vibrate in a particular mode and/or direction. However, any other suitable material and/or method may be used to encourage the desired type of vibration and/or fluid flow resulting from the vibration of the flexible membrane 2.

The flexible membrane 2 preferably is of a material that does not plastically deform from the vibrations and/or oscillations caused by interactions of the first and second magnetic fields in the first preferred embodiment and the movement caused by the shape changing material 30 in the second preferred embodiment. The material used for the flexible membrane 2 is also preferably of a relatively high elasticity (for example, a rubber material, a woven fabric material, or a relatively thin film material such as ripstop nylon, superthin polyester film, mylar-coated taffeta, Kevlar tapes, or polyethylene film) that allows for a large range of vibrational and/or oscillation amplitude without plastic deformation of the flexible membrane 2. Alternatively, the flexible membrane 2 may be composed of a relatively stiffer material that still allows for vibrations and oscillations such as spring steel, aluminum, silicon, or beryllium copper. In the MEMS scale of the fan 100, the flexible membrane 2 is preferably made of a material commonly used in MEMS manufacturing, for example, etched wafer, silicon, beryllium copper, steel, or any other suitable MEMS manufacturing material, and may also be made of the same material as the support structure 6. The flexible membrane 2 may also include a conductive flexible material, for example, a sheet of copper, a printed circuit, or a non conductive material that is coated with a conductive coat, for example, Indium Tin Oxide (ITO). The flexible membrane 2 is preferably composed of one material, but may alternatively be composed of a plurality of material types. For example, the material at the supported ends may be of a material with higher stiffness than the other portions of the flexible membrane 2 to increase ease of fixation and/or the durability of the flexible membrane 2. Alternatively, the flexible membrane 2 may include a portion that is reinforced with a second material. For example, a second material may be coupled to the flexible membrane 2 at the supported ends to increase ease of fixation and/or the durability of the flexible membrane. However, the material of the flexible membrane 2 may be of any other suitable type or combination of types.

Because the flexible membrane 2 is fixed on at least two ends 22 and 24 and vibrates, the flexible membrane 2 may provide a more compact alternative to a bladed fan that is typically used for cooling. Additionally, because of the substantially aerodynamic shape of the typical fan blade (relatively thin at the leading edge), an exposed rotating fan blade may potentially injure a user. The movement of the flexible membrane 2 to cause fluid flow is substantially in a direction that does not result in a relatively sharp leading edge. As a result, the flexible membrane 2 may be less likely to injure a user.

The support structure 6 functions to support the supported ends 22 and 24 of the flexible membrane 2. The support structure 6 preferably also functions to provide a tension between the supported ends 22 and 24 of the flexible membrane 2. Alternatively, the support structure 6 may support the supported ends 22 and 24 without providing a tension between the supported ends 22 and 24 or to provide a slight tension between the supported ends 22 and 24. However, any other suitable tension may be provided between the two supported ends 22 and 24 by the support structure 6. The supporting structure 6 preferably includes a base 8 and, in the first preferred embodiment, a section for receiving at least one of the first and second magnets. The tension applied to the membrane 2 is preferably a function of the elasticity of the membrane 2 and the physical characteristics (i.e., young's modulus, etc.) of the base 8, along with the particular distance between the ends of the base 8. As shown in FIGS. 1 and 2, the base 8 may be shaped as a bow. The bow-shaped base provides an approximately constant tension on the membrane 2 over short deviations. So, as the membrane 2 stretches over time, the spring-action of the base 2 ensures that the membrane 2 remains at a particular tension. It is understood that other shapes of bases may be used to implement the fan 100. A flat unbowed base can also be used, and the natural elasticity of the membrane 2 may serve this same purpose. In another embodiment, constant force springs (such as Belleville washers) or compliant mechanisms may be attached to the ends of the membrane or incorporated into the structure of the base itself, so that a relatively constant tension on the membrane 2 can be maintained over longer periods of time. For embodiments where the membrane is vertically oriented, a constant restoring force can be generated with gravitational attraction, by attaching weights to the membrane 2 or base 8. The base 8 may be continuous with the membrane 2, but may include a different geometry than the membrane 2 (shown in FIG. 7), which may be useful in a MEMS application where the fan 100 may be of a scale that is relatively difficult to assemble. By forming both the base 8 and the flexible membrane 2 in one piece, manufacturing may be simplified and the need for post assembly is decreased. Similarly, the need for additional fasteners to couple the flexible membrane 2 to the support structure 6 may be decreased. As shown in FIG. 7, the supported ends 22 and 24 of the flexible membrane are formed in the manufacturing process and is preferably of a geometry that allows the membrane 2 to vibrate and/or oscillate (for example, thinner cross section than both the flexible membrane 2 and the base 8). This variation of the fan 100 is preferably of one continuous material, for example, etched from a wafer. The etching may include an etching step (shown in FIG. 7 a) and a folding step (shown in FIG. 7 b) to form the full base 8 and flexible membrane 2 assembly.

In one variation, the support structure 6 may also function to increase the effective cooling of provided by the fan 100. In a first example, the support structure 6 may include a geometry that effectively directs the fluid flow created by the flexible membrane 2, such as a nozzle that directs and concentrates the airflow created by the flexible membrane 2 to a particular location. In a second example, the support structure 6 may function to direct airflow in a particular direction by way of a partial housing around the oscillating membrane 2, as shown in FIG. 8. As shown in FIGS. 8 a and 8 b, the support structure may function to direct flow in more than one direction. In this example of the support structure, the support structure may direct fluid flow perpendicular to the long axis of the membrane 2, parallel to the long axis of the membrane 2, or in any other suitable direction. However, any other suitable flow direction geometry may be used. In another variation, the support structure 6 may function as a heat sink for the component that is to be cooled. In a first example, the support structure 6 may function to disperse heat towards a plurality of flexible membranes 2 that then create a fluid flow to disperse the heat further. In a second example, the flexible membranes 2 may function as fins for the heat sink. However, any other suitable arrangement of the support structure 6 may be used.

The fan 100 may also include an adjustable tension provider, such as a motor, a temperature dependent material or any other suitable type of shape changing material, a displacement device coupled to the membrane 2, or any other suitable type of device, configured to apply an adjustable tension force between the supported ends of the membrane according to the speed of the fluid flow and/or the temperature of the surrounding environment or object to be cooled. The tension provider may be coupled to the base 8, but may alternatively be located in any other suitable location. The tension of the membrane 2 may be adjusted in response to desired characteristics of the fluid flow that the fan 100 produces, for example, the velocity of the produced fluid flow and/or the amount of fluid that is moved. In particular, it is advantageous to vibrate the flexible membrane 2 at the resonant frequency of the flexible membrane 2. This allows for a substantially high efficiency of the fan 100 as the power necessary to maintain the vibration of the flexible membrane 2 is substantially less at the resonant frequency than at a non-resonant frequency. The tension of the flexible membrane 2 may control the resonant frequency of the flexible membrane 2. For example, when held at a first tension, the flexible membrane 2 may have a first resonant frequency, and when held at a second tension, the flexible membrane 2 may have a second resonant frequency. The first resonant frequency may correspond to a particular desired characteristic of the fluid flow, and, as a result, tension provider may adjust the tension of the flexible membrane 2 to the first tension in order to provide the particular desired characteristic of the resulting fluid flow. This system and method of controlling the characteristics of the resulting fluid flow of the fan 100 provides a substantial advantage over typical vibration fans, such as cantilevered piezoelectric fans that are well known in the art. The piezoelectric material typically used in cantilevered piezoelectric fans have a particular resonant frequency that is a characteristic of the material, limiting the characteristics that are available from the resulting fluid flow.

Multiple fans 100 can also be used to provide increased fluid flow for a given area or application. For example, in the MEMS scale, an array of fans 100 may be located in a layer underneath the processing unit to facilitate cooling as substantial amount of the surface area of the processing unit. A cost effective variation of the first preferred embodiment involves the use of two membranes 2 a and 2 b, each with first magnet 11 a and 11 b, where each membrane 2 a and 2 b is placed on opposite sides of a second magnet 14, as shown in FIG. 9. This arrangement allows for the utilization of both poles of the first magnetic field. A multitude of these fans boo may be stacked onto a tower or arranged in a framework to provide fluid flow over a large area, and not just providing air flow in one direction as typically seen in fans known in the art. Alternatively, more than one flexible membrane 2 may be supported by a support structure 6. For example, two flexible membranes 2 may be supported by a support structure 6. The two flexible membranes 2 in this example may vibrate in phase to move a higher volume of fluid, but may alternatively vibrate 180 degrees out of phase, where the two flexible membranes 2 come together and apart, which may increase the fluid flow rate. The plurality of membranes 2 may be connected and wrapped around a support structure 6, but may alternatively be individual membranes 2. However, any other suitable arrangement of multiple fans boo may be used.

The fan 100 may also include a rotating element 40, for example, as shown in FIGS. 10 a and 10 b, that rotates the flexible membrane 2. The rotating element 40 is preferably coupled to the flexible membrane 2 through the support structure 6, but may alternatively be coupled to the flexible membrane 2 through any other suitable mechanical connection. In a first variation, the rotating element 40 rotates the flexible membrane 2 about an axis substantially perpendicular to the long axis 20 of the flexible membrane 2, as shown in FIG. 10 a. In this variation, the support structure 6 may include wheels mounted substantially along the long axis 20 that run along a circular track to rotate the flexible membrane 2. The track may also include bearings to facilitate the rotation. However, any other suitable mechanism may be used to rotate the flexible membrane 2 about an axis substantially perpendicular to the long axis 20 of the flexible membrane 2. Rotation of this first variation may result in a stream of fluid flow that spirals away from the fan 100. In a second variation, the rotating element 40 rotates the flexible membrane about an axis substantially collinear to the long axis 20 of the flexible membrane 2, as shown in FIG. 10 b. In this variation, a motor may be coupled to the support structure 6 to rotate the support structure 6 and the flexible membrane 2. Alternatively, the motor may function as the interface between the support structure 6 and the flexible membrane 2, forming a supported end of the flexible membrane 2 and rotating the flexible membrane 2 relative to the support structure 6. In either the first or second variations, the rotating element may be a motor, but alternatively, the rotating element may be an off center mass coupled to the flexible membrane 2 that, when oscillated, causes a torque on the membrane to cause the membrane to rotate. However, any other suitable mechanism to rotate the flexible membrane 2 about an axis substantially collinear to the long axis 20 of the flexible membrane 2 may be used. Rotation of this second variation may be used to direct fluid flow in particular directions and/or create a plurality of fluid flows in different directions that superimpose to form a fluid flow of a desired characteristic.

1. First Preferred Embodiment

The fan 100 of the first preferred embodiments preferably utilizes electromagnetic forces to move air. In particular, the interaction between the first and second magnetic fields of the first and second magnets 12 and 14 respectively function to vibrate the flexible membrane 2 at a frequency to move air. As described above, the vibration of the flexible membrane 2 functions to move air in a direction substantially perpendicular to the long axis 20. The first magnet 12 is preferably a permanent magnet and is preferably mounted to the flexible membrane 2. In a first variation of the first preferred embodiment, the second magnet 14 preferably includes a conductor 4 and a power source 5 that provides an electrical current through the conductor 4 to form the second magnetic field. The power source 5 preferably adjust the electrical current through the conductor 4 to fluctuate the second magnetic field relative to the first magnetic field to create a force that acts between the first magnet 12 and the second magnet 14. Because the first magnet 12 is mounted onto the flexible membrane 2, the flexible membrane 2 is caused to vibrate or oscillate, translating electricity into a force that moves a fluid, such as air or water. The conductor 4 is preferably oriented so as to project the first magnetic field (i.e., pole to pole axis) substantially collinear to the second magnetic field, as shown in FIGS. 11 a and 11 b. Alternatively, the first magnetic field may be oriented to be perpendicular to the second magnetic field, as shown in FIG. 11 c. However, any other suitable relative orientation between the first and second magnetic fields may be used. Alternatively, the second magnet 14 may be coupled to the flexible membrane 2 and the first magnet 12 may be coupled to the support structure 6. However, any other suitable arrangement of the first and second magnets 12 and 14 may be used. The fan 100 may also include any suitable combination of a plurality of first magnets 12 and second magnets 14 (in particular, conductors 4, and/or power sources 5). For example, a conductor 4 may be placed on opposite sides of a first magnet 12 that is coupled to the flexible membrane 2, as shown in FIG. 12, which may produce a stronger vibration or oscillation of the flexible membrane 2.

In the first variation of the first preferred embodiment, the power source 5 supplies a current through the conductor 4, generating the first magnetic field. In other words, the power source 5 and the conductor 4 cooperatively function as the second magnet 14. The magnetic poles of the first magnetic field preferably alternates between a first orientation that attracts the first magnet 12 located on the flexible membrane 2 and a second orientation that repels the first magnet 12, creating an oscillation or vibration in the flexible membrane 2. The power source 5 preferably supplies an alternating current (AC) through the conductor 4 to create the alternating first and second orientations of the first magnetic field, as shown in FIGS. 11 a and 11 b. The alternating current may be substantially a sine wave, but may alternatively be square wave, a triangular wave, pulse-width modulated signals, pulsed direct currents, or any other suitable fluctuating current. The current provided by the power source 5 may also be adjusted based on the detected vibration of the flexible membrane 2. For example, if the flexible membrane 2 is detected to be out of phase or vibrating at a frequency other than the desired frequency (for example, if an outside air current is providing an unpredicted force), the power source 5 may function to modulate the current provided to the conductor 4 to correct the vibration. The vibration of the flexible membrane 2 may be detected by monitoring the first magnetic field, for example, through a Hall effect sensor or any other suitable type of sensor, but may alternatively be detected using any other suitable method and/or system. The alternating current may also be adjusted based on the desired fluid flow from the fan 100. For example, for a higher fluid flow, the alternating current may be adjusted to a higher frequency. This may provide another substantial advantage over typical vibration fans, such as cantilevered piezoelectric fans that are well known in the art. As mentioned above, the piezoelectric material typically used in cantilevered piezoelectric fans have a particular resonant frequency that is a characteristic of the material, limiting the characteristics that are available from the resulting fluid flow. The alternating current provided by the current generator is preferably substantially similar to the natural resonance frequency of the membrane 2 (which may be adjusted by the tension provider, as described above) to create an oscillation of the membrane 2 that may be sustained by the “push and pull” provided by the interaction of the first and second magnetic fields. However, any other suitable frequency may be used.

The power source 5 of the first variation of the first preferred embodiment functions to induce vibration in the membrane 2. Preferably, the power source 5 creates an electric current through the conductor 4 and induces a first electromagnetic field associated with the conductor 4. In one version, the power source 5 includes an alternating current (“AC”) power source. The power source of this version may include a conditioning circuit to adjust the frequency of the alternating current. In another version, the power source 5 includes a direct current (“DC”) power source, such as a battery (e.g., lithium ion, lithium polymer, nickel cadmium, or lead acid) or solar panel. The power source 5 of this version may include an inverter (DC/AC). The power source 5 may, however, be any suitable arrangement of suitable power sources and conditioning circuits or other devices to induce vibration in the membrane 2. The fan 100 may be used as part of an electronic device (such as a computer). In this variation, the power source 5 may also power the other components of the electronic device. As mentioned above, the fan 100 may also include any suitable combination of any number of conductors 4 and magnetic field generators 12. The power source 5 preferably supplies a current to each of the conductors 4, but may alternatively include a plurality of individual power cells that each supply current to a conductor 4.

The conductor 4 is preferably a coil of conductive wire or a plurality of individual conductive wire, preferably of copper or aluminum. The conductor 4 is preferably coupled to the support structure 6 by a fastener, for example, a screw, a bolt, adhesive, or any other suitable fastener. The conductor 4 is preferably electrically coupled to a power conditioning circuit (described below). The coils are preferably wound in a cylindrical form or a rectangular form, but may be of any suitable shape, configuration or form. The coils may also be filled with ferrite powder or laminated ferrous metals to enhance flux through the coils. However, any other suitable variations of the conductor 4 may be used to enhance the performance of the fan 100 for particular applications.

The first magnet 12 is preferably oriented such the first and second magnetic fields are substantially collinear. The first magnet 12 may be composed of any suitable magnetic field generating material. The first magnet 12 is preferably of a permanent magnet that retains magnetic field generation properties without electricity, allowing the first magnet 12 to be coupled to the flexible membrane 12 without wires that may fail as the membrane 2 oscillates. NdFeB rare earth magnets, ceramic magnets, Alnico magnets, and Samarium-cobalt magnets are a few of the options. Also, as is well known in the art, the magnetic field produced by the permanent magnet can be made into a “complete circuit” by appropriately placing laminated or powdered ferromagnetic or ferromagnetic materials in the proximity of the magnetic field produced by the first magnet 12. This technique ensures that the maximum magnetic field can be directed to the area of the coils. However, any other suitable magnetic field generating material or method may be used. Alternatively, the first magnet 12 may be an electromagnet (also known as a field coil in generator applications). The electromagnets may include one or more coils of wire with either air cores or with ferromagnetic cores may function as the field coils. Alternatively, the first magnet 12 may include a conductor that is imbedded into the flexible membrane 2. The power source 5 preferably provides a current through the coil of the first magnet 12 to strengthen the magnetic field. However, the electromagnet may be powered with a second power source or any other suitable power source.

In the variation of the fan 100 where the flexible membrane 2 is composed of a conductive material, the flexible membrane 2 may also function as the first magnet 12. The power source may provide a circuit through the conductive membrane 2, thus creating the second magnetic field. This variation may allow for more compact scales of the fan 100, for example, on a MEMS scale as shown in FIG. 7 where coupling a permanent magnet or an electromagnet is difficult. By utilizing the membrane 2 to create movement in the fluid as well to create the second magnetic field, the complexity and the cost of the fan 100 may also decrease.

As current is sent through the conductor 4, the forces that result from the initial interaction of the first and second magnetic fields may cause the membrane 2 to move irregularly and the membrane may twist or sway or any other possible type of irregular movement until the natural oscillation frequency of the membrane 2 is reached. To decrease the magnitude and/or the sustained length of time of the irregular movement, the fan 100 may further include at least one mass 62 attached to the membrane 2 to stabilize movements or vibrations of the membrane 2, similar to the mass as shown in FIG. 6. The mass 62 may include one or more low-profile objects of either symmetric or asymmetric shape. For membranes with larger sizes, the attached mass 62 may provide a more vigorous oscillation of the membrane 2. In some cases, the mass 62 may act to decrease the instability in the movement of the membrane at the onset of oscillation. However, the location and geometry of the mass 62 and the tension, width, and length of the membrane 2 can be made such that any instability in the movement of the membrane 2 are quickly transformed into an oscillation of the first normal mode with reduced torsional oscillation relative to the translational oscillation.

In a second variation of the first preferred embodiment, the fan 100 may include a magnet displacement device 50 that is coupled to the second magnet 14. The magnet displacement device 50 functions to displace the second magnet 14 relative to the first magnet 12, fluctuating the second magnetic field as seen by the first magnetic field and causing the flexible membrane 2 to vibrate. The second variation of the flexible membrane is otherwise substantially similar or identical to the first variation of the flexible membrane. The magnet displacement device 50 may be a motor that rotates the second magnet 14, as shown in FIG. 13, or, alternatively, a linear actuator that moves the second magnet 14 to and from the first magnet 12. However, any other suitable type of displacement device may be used to move the second magnet 14 relative to the first magnet 12. Alternatively, the magnet displacement device 50 may function to move the first magnet 12 or both the first and second magnets 12 and 14 or any other suitable arrangement.

The fan 100 of the first preferred embodiment effectively concentrates the input energy to create oscillation of the entire flexible membrane 2 at one or more discrete zones. This mechanism works in a similar fashion to the way in which oscillating a lever towards the base of the lever for a small distance translates to a larger motion of the lever farther away from the base. The smaller travel distance necessary to create larger motion by the center of the membrane 2 by oscillating the end of the membrane is what allows for the use of smaller magnetic field generators 12 and smaller conductors 4. Because the first magnet 12 (or the conductor 4) is coupled to the flexible membrane 2, by using a smaller first magnet 12 (or conductor 4), less weight is added to the flexible membrane 2 and dampening of the oscillations and/or vibrations of the membrane 2 is decreased. In addition, smaller first and second magnetic fields are needed to fill the smaller volume of space through which the end of the membrane 2 may travel, which translates to lesser material costs. Additionally, by placing the first magnet 12 and the second magnet 14 largely out of the center of the membrane 2, the fan 100 may be more effective at moving fluid. Similarly, the highest flow rate produced by the fan 100 is located substantially towards the center of the flexible membrane 2. To utilize the highest flow rate produced, the object to be cooled (for example, a chip or other electronics) may be located substantially adjacent to the center of the flexible membrane. Because some electrical components may be sensitive to magnetic fields, by placing the first and second magnet 12 and 14 largely out of the center of the membrane 2, the magnetic field generating components of the fan 100 may be placed substantially distant from the electromagnetically sensitive components. This may provide an advantage over typical rotating fans where the magnets driving the blades are substantially close to the blades and are placed substantially close to potentially electromagnetically sensitive components.

2. Second Preferred Embodiment

The fan 100 of the second preferred embodiment preferably uses shape changing material to cause vibration in the flexible membrane 2 to move air. In particular, the shape changing material 30 of the flexible membrane 2 preferably induces the flexible membrane 2 to vibrate at a resonant frequency to move air in a direction substantially perpendicular to the long axis of the flexible membrane 2. As shown in FIGS. 2 a and 2 b, the fan 100 of the second preferred embodiments includes a flexible membrane 2 where at least a portion of the flexible membrane includes a shape changing material 30. The shape changing material 30 may be mounted onto the membrane material, or may alternatively be integrated into the membrane material and/or form a portion of the membrane 2. As shown in FIG. 2 a, the shape changing material 30 may be located substantially along the entire length of the flexible membrane 2, for example, on one side of the long axis 20. As shown in FIG. 2 b, the shape changing material may be located substantially adjacent to one of the supported ends 22 or 24 of the flexible membrane. This variation is similar to the fan 100 of the first preferred embodiment where the fan 100 concentrates the energy to create oscillation of the entire flexible membrane 2 at one or more discrete zones. This works in a similar fashion to the way in which oscillating a lever towards the base of the lever for a small distance translates to a larger motion of the lever farther away from the base. The smaller travel distance necessary to create larger motion by the center of the membrane 2 by oscillating the end of the membrane is what allows for the use of smaller shape changing material, which may decrease the overall cost of manufacturing as well as the required power to operate the shape changing material. However, the shape changing material 30 may be arranged in any other suitable manner relative to the flexible membrane 2.

The fan 100 of the second preferred embodiment may also include a second shape changing material 32 that cooperates with the shape changing material 30 to vibrate the flexible membrane 2 at a frequency, as shown in FIG. 2 a. In a first example, the second shape changing material 32 and the shape changing material 30 may be of different shape changing characteristics. The same voltage may be applied to both shape changing materials 30 and 32 and the resulting shape change may be different, such as one will bend more than the other, resulting in a warping of the flexible membrane 2 that, when the motion is repeated, may result in a vibration of the flexible membrane 2. In a second example, the power supply 5 may function to supply different voltages to each of the shape changing materials 30 and 32 (for example, a sine wave that is 180 degrees out of phase) that may result in a vibration of the flexible membrane 2. However, any other suitable cooperation between shape changing materials 30 and 32 to cause a vibration in the flexible membrane 2 may be used.

In a first variation of the second preferred embodiment, the power source 5 functions to provide a current to the shape changing material to change the shape. In this variation, the shape changing material changes shape with an applied current or voltage, for example, an electroactive polymer or a piezoelectric material. In another example, the shape changing material 30 may include a memory metal such as Nickel Titanium (NiTi) and that changes shape with the addition of a voltage and/or a change in temperature, causing vibration in the membrane 2 or a dielectric elastomer that induces strain onto a portion of the membrane 2 to cause vibration. In a second variation, the power source 5 functions to provide a temperature change (for example, an increased temperature or decreased temperature). In this variation, the shape changing material changes shape with the temperature, for example, a bimetallic strip that includes two materials with substantially different expansion properties when subjected to heat or any other suitable energy input that are bonded to each other. As one of materials is expanded, the bimetallic strip may change shape, causing vibration in the membrane 2. In this variation, the temperature sensitive shape changing material may also function to detect the temperature of the air substantially adjacent to the fan 100, for example, by monitoring the magnitude of the shape change of the shape changing material 30, decreasing the need for additional temperature sensors. However, any other suitable material or method to induce vibration in the membrane 2 may be used.

The fan 100 of the second preferred embodiment may alternatively utilize the heat provided by the element that is to be cooled to power the shape changing material 30. For example, the flexible membrane 2 may be arranged such that a first edge of the shape changing material 30 is located more proximal to the hot element to be cooled than a second edge. As a result, the first edge of the shape changing material is heated faster than the second edge. In this variation, the shape changing material is preferably a material that changes shape with the temperature. As the first edge reaches a higher temperature faster than the second edge, the shape changing material 30 starts to warp, which may cause a movement in the flexible membrane 2. However, any other suitable type of shape changing material 30 and/or any other suitable method for actuating the shape changing material 30 may be used.

3. Power Management Circuit

The fan 100 of the preferred embodiments may include a power management circuit that is electrically coupled to power source 5 of the first and second preferred embodiments. The power management circuit preferably takes an input for the desired power of the fan or the amount of fluid desired to be moved by the fan and preferably adjusts the amount of power provided to the fan 100. In particular, the power management circuit preferably adjust the amount of power provided to the first and/or second magnet 12 and 14 of the first preferred embodiment and to the shape changing material 30 of the second preferred embodiment. In the first preferred embodiment, the power management circuit may adjust the current through the conductor 4 to increase the strength of the second magnetic field. In other words, because the current through the conductor 4 is preferably an alternating or pulsed direct current, the amplitude of the alternating current is preferably increased, creating increased attraction and repulsion forces between the first magnet 12 and the second magnet 14 and increasing the amplitude of the oscillation of the membrane 2 and the amount of fluid that is moved by the fan 100. In the variation of the first preferred embodiment where the first magnet 12 is also an electromagnet, the power management circuit also preferably adjusts the magnitude of the current through the electromagnet, creating a stronger second magnetic field that contributes to the attraction and repulsion forces to affect the amplitude of oscillation of the membrane 2. In the second preferred embodiment, the power management circuit may increase the temperature proximal to the shape changing material 30 that changes shape due to temperature changes to increase the amplitude of the vibration of the flexible membrane 2. The power management circuit may alternatively increase the rate of temperature change to increase the frequency of the vibration of the flexible membrane 2. The power management circuit may also alternatively adjust the voltage across a shape changing material 30 that changes shape due to electric potential, for example, a shape changing material composed of electroactive polymers, dielectric elastomers, or piezoelectric materials. However, the power management circuit may control the vibration of the flexible membrane 2 using any other suitable means and/or method.

The power management circuit may also function to receive a command for the direction of fluid movement. For example, the alternating current supplied to the conductor 4 of the first preferred embodiment may be a normal symmetric sine wave to create substantially equal attraction and repulsion forces with the first magnet 12, but may alternatively be asymmetric such that the attraction and repulsion forces created with the first magnet 12 are not equal. This may create an oscillation of the membrane 2 that moves a greater distance in a first direction than in a second direction, affecting the movement of the fluid across the membrane 2. Similarly, in the variation of the second preferred embodiment with two shape changing materials 30 and 32, the power management circuit may function to adjust the power supplied to each of the shape changing materials 30 and 32 to create the desired displacement along different portions of the flexible membrane 2 that may result in the desired oscillation of the membrane 2. The power management circuit may also function to monitor the movement of the membrane 2. For example, if an irregular or undesired oscillation in the membrane 2 is detected, the current supplied to the conductor 4 or the shape changing material 30 may be adjusted to regulate the movement of the membrane 2 and regain the desired oscillation. This may be useful in scenarios where the fan 100 is used in environments where fluid is already flowing, for example, outdoors on a windy day. The power management circuit preferably also functions to modulate the current through the conductor 4 to stop the movement of the membrane 2. To stop the membrane 2, the power management circuit may cause the alternating current that is sent to the conductor 4 to become 180 degrees out of phase from the alternating current to cancel momentum of the existing oscillation of the membrane 2. Alternatively, a direct current may be sent to the conductor 4, no longer providing the alternating first magnetic field and thus no additional force is provided to the membrane to continue to oscillate. The direct current may also cause the membrane to become substantially attracted to the conductor 4, thus pulling the membrane 2 towards the conductor 4 and preventing further movement. However, any other suitable method to stop the movement of the membrane 2 may be used. However, the power management circuit may perform any other suitable functions to regulate the performance of the fan 100.

While the fan 100 is preferably one of the two embodiments described above, the flexible membrane 2 may be induced to vibrate using any other suitable method. For example, a solenoid may be coupled to the flexible membrane 2 and oscillated to induce vibration in the flexible membrane 2. In a second example, a linear actuator may be coupled substantially collinear with and between the flexible membrane 2 and the support structure 6. As the linear actuator moves, the tension on the flexible membrane 2 is changed, which may induce vibration in the flexible membrane. However, any other suitable membrane displacement device may be used.

The flexible membrane may alternatively be a wire that is substantially cylindrical with two supported ends. Using the displacement methods as described above or any other suitable type of displacement method, the wire may be induced to vibrate to cause vortices to cause fluid flow. However, any other suitable variation of the flexible membrane geometry may be used.

As a person skilled in the art will recognize from the previous detailed description and from the figures and claims, modifications and changes can be made to the preferred embodiments of the invention without departing from the scope of this invention defined in the following claims. 

1. A non-propeller fan that moves a fluid, comprising: a flexible membrane including two supported ends and a length between the two supported ends that defines a long axis; a support structure that supports the two supported ends of the flexible membrane; a first magnet that generates a first magnetic field; and a second magnet that generates a second magnetic field that interacts with the first magnetic field and fluctuates relative to the first magnetic field to cause the membrane to vibrate at a frequency and to move the fluid in a direction substantially perpendicular to the long axis of the flexible membrane.
 2. The fan of claim 1, wherein the flexible membrane vibrates with a bending motion.
 3. The fan of claim 1, wherein the flexible membrane vibrates with a torsional motion.
 4. The fan of claim 1, wherein the fluid is air.
 5. The fan of claim 1, wherein the flexible membrane is asymmetric across the long axis.
 6. The fan of claim 1, wherein the flexible membrane includes a weight coupled to the membrane.
 7. The fan of claim 6, wherein the weight is arranged substantially to one side of the long axis.
 8. The fan of claim 1, wherein the first magnet is coupled to the flexible membrane and the second magnet is coupled to the support structure.
 9. The fan of claim 8, wherein the first magnet is located substantially along the long axis.
 10. The fan of claim 8, wherein the first magnet field also fluctuates relative to the second magnetic field.
 11. The fan of claim 10, wherein the first magnet includes a conductor that is coupled to the flexible membrane and a power source that supplies an alternating electric current to the conductor to form a fluctuating first magnetic field.
 12. The fan of claim 1, further comprising a magnet displacement device coupled to the second magnet, wherein the magnet displacement device moves the first magnet relative to the second magnet to fluctuate the second magnetic field relative to the first magnetic field.
 13. The fan of claim 12, wherein the magnet displacement device is a rotational motor that rotates the second magnet relative to the first magnet to fluctuate the second magnetic field relative to the first magnetic field.
 14. The fan of claim 12, wherein the magnet displacement device is a linear actuator that moves the second magnet relative to the first magnet to fluctuate the second magnetic field relative to the first magnetic field.
 15. The fan of claim 1, wherein the second magnet includes a conductor and a power source that supplies an alternating electric current to the conductor to form a fluctuating second magnetic field.
 16. The fan of claim 1, wherein the membrane includes a main surface that defines a rest plane at rest and the fluid is moved in a direction substantially parallel to the rest plane of the flexible membrane.
 17. The fan of claim 1, wherein the support structure provides a tension between the two supported ends of the flexible membrane.
 18. The fan of claim 17, further comprising a tensioning device that adjusts the tension of the flexible membrane between the two fixed points, wherein the tension determines the vibration frequency of the flexible membrane.
 19. The fan of claim 1, wherein the support structure directs the flow generated by the vibration of the membrane.
 20. The fan of claim 1, further comprising a rotation device that rotates the flexible membrane.
 21. The fan of claim 20, wherein the rotation device is coupled to the support structure.
 22. The fan of claim 20, wherein the rotation device rotates the flexible membrane about an axis substantially collinear to the long axis of the flexible membrane.
 23. The fan of claim 20, wherein the rotation device rotates the flexible membrane about an axis substantially perpendicular to the long axis of the flexible membrane.
 24. A non-propeller fan that moves a fluid, comprising: a flexible membrane including two supported ends and a length between the two supported ends that defines a long axis, wherein at least a portion of the length of flexible membrane includes a shape changing material; a support structure that supports the two supported ends of the flexible membrane; a power source coupled to the shape changing material of the flexible membrane that provides power to change the shape of the shape changing material to vibrate the flexible membrane at a frequency and to move the fluid in a direction substantially perpendicular to the long axis of the flexible membrane.
 25. The fan of claim 24, wherein the support structure provides a tension to the flexible membrane between the two supported ends.
 26. The fan of claim 24, wherein a second portion of the length of flexible membrane includes a second shape changing material, and wherein the shape changing material and the second shape changing material cooperate to vibrate the flexible membrane at a frequency.
 27. The fan of claim 26, wherein the shape changing material and the second shape changing material are of substantially different shape changing characteristics, and wherein the differences in shape changing characteristics cooperate to vibrate the flexible membrane at a frequency.
 28. The fan of claim 24, wherein the shape changing material is arranged along substantially the entire length of the flexible membrane between the two supported ends.
 29. The fan of claim 24, wherein the shape changing material is arranged substantially proximal to at least one of the supported ends.
 30. The fan of claim 24, wherein the shape changing material is mounted to the flexible membrane.
 31. The fan of claim 24, wherein the power source provides heat to the shape changing material to change the shape of the shape changing material.
 32. The fan of claim 24, wherein the power source provides a voltage to the shape changing material to change the shape of the shape changing material.
 33. The fan of claim 32, wherein the shape changing material is material selected from the group consisting of: electroactive polymer and piezoelectric material.
 34. A method for generating movement in a fluid, comprising: providing a flexible membrane including two supported ends and a length between the two supported ends that defines a long axis; tensioning the flexible membrane between the two supported ends; and vibrating the flexible membrane at a frequency to move the fluid in a direction substantially perpendicular to the long axis of the flexible membrane.
 35. The method of claim 34, further comprising rotating the membrane.
 36. The method of claim 35, wherein the step of rotating the membrane includes rotating the membrane about an axis substantially collinear to the long axis.
 37. The method of claim 35, wherein the step of rotating the membrane includes rotating the membrane about an axis substantially perpendicular to the long axis. 